Drafting tool



April 30, 1968 J. NORBEDO DRAFTING' TOOL Filed Nov. 17, 1966 A TTOR/VEY United States Patent 3,380,164 DRAFTING TOOL Joseph Norbedo, 300 Summit Ave., Brighton, Mass. 02135 Filed Nov. 17, 1966, Ser. No. 595,257 2 Claims. (CI. 33-42) ABSTRACT OF THE DISCLOSURE A flat substantially rectangular sheet plastic tool having a curved edge and an opening for a line drawing instrument arranged so that when the tool is moved along a guide the line drawn will be parallel to and equidistantly spaced from the guide. Arranged so that an inked line will not be smeared by movement of the tool in the direction of the line being drawn.

This invention relates to a drafting tool and more particularly to a drafting tool for drawing lines parallel to straight or curved guide surfaces.

The invention has for an object to provide a novel and improved drafting tool of the character specified for use in drawing lines parallel to straight and curved guide surfaces in a simple and efiicient manner.

The invention has for another object to provide a novel and improved drafting tool of the character specified adapted for use with either a pencil or a drafting pen, the tool being of a structure such as to avoid contact with the line as it is being drawn whereby to prevent smearing or smudging thereof.

With these general objects in view and such others as may hereinafter appear; the invention consists in the drafting tool as hereinafter described and particularly defined in the claims at the end of this specification.

In the drawings illustrating the preferred embodiment of the invention: I

FIG. 1 is a plan view of a drafting tool embodying the present invention;

FIG. 2 is a side view of the tool shown in FIG. 1;

FIG. 3 is an end view of the same;

FIG. 4 is a plan view of a modified form of the tool; and

FIG. 5 is a plan view showing the present tool in use for drawing lines parallel to curved guide surfaces.

In general, the present invention contemplates a drafting tool for drawing lines parallel to straight or curved guide surfaces and which is adapted for use with either pen or pencil. The present drafting tool is of the type provided with an opening for receiving the drafting instrument, the opening being spaced from the side of the tool in engagement with the guiding edge so that when the drafting instrument is placed in the opening and moved along with the tool, a line parallel to the guiding edge is produced. So far as applicant is aware, prior drafting tools of this type are of a structure such that the undersurface of the tool will drag along over the line drawn so as to obviate its use with India ink or the like. In accordance with one feature of the present invention the tool is of a structure such as to avoid contact with the line drawn whereby to prevent smearing or blurring of the inked line. The tool may also be used with a ball point pen.

The present drafting tool may be made of plastic, metal or other suitable material and is further characterized by its ability to maintain parallelism with its guiding edge or surface as it is moved around concave, convex or circular surfaces as well as straight guide surfaces. In practice, the engaging sides of the tool are conveXly curved to enable the same to be moved along cone-ave surfaces. The position of the opening relative to a point of tangency of the curved engaging surface with the guiding edge is such as to maintain parallelism of the line drawn with the guiding edge along either straight or curved surfaces. In practice, different sizes of the present drafting tool may be provided to enable parallel lines to be drawn at different spaced distances from the guiding surface or edge.

Referring now to the drawings, 10 represents the present drafting tool which is of a generally rectangular shape in plan elevation, the tool being greater in length than in width, and is relatively thin in cross section. The tool is provided with an opening 12 adjacent its lower edge 14 which may be termed the trailing edge in accordance with the manner in which the tool is used. The opening 12, shown as a circular opening in FIG. 1, and into which the drawing instrument is inserted, is offset from a longitudinal center line, and opposed longitudinal sides 16, 18 of the tool are convexly curved, as illustrated, the curved sides comprising the edges to be engaged with a guiding surface in drawing parallel lines. The upper or leading edge 20 of the drafting tool is also curved, as shown, to join the curved ends of the engaging sides 16, 18. The lower or trailing edge 14 is straight as shown.

In use, when an engaging side 16, for example, is placed against a guide surface, such as a straight edge indicated at 22, and a drafting instrument, such as a pen or pencil, is placed at the inner edge of the circular opening 12 at a point 24, the tool may be moved with the drawing instrument along the guide surface in the direction of the arrow to draw a line parallel to the straight edge. The proportions of the tool are such that the point of tangency between the curved engaging edge 16 and the straight edge 22, as indicated at 26, is disposed forwardly of the point of contact 24 of the drafting instrument with the inner edge of the opening 12 when the tool is moved forwardly with the drafting instrument. In operation, the curved edge 16 is in frictional engagement with the straight edge 22, and as the tool is moved in the direction of the arrow, it becomes balanced so as to maintain the point of tangency 26 without rocking whereby to maintain parallelism of the line being drawn with the guiding edge 22. In other words, when the drafting instrument is moved forwardly in the direction of the arrow, the tool will tend to rock forwardly about the point 24 until the convexly curved engaging edge 16 in frictional engagement with the straight edge reaches the point 26 where the frictional engagement and the force of the forward movement become balanced to maintain the parallelism.

Since the opening 12 is offset in a direction toward the engaging edge 16, the parallel line drawn will be spaced relatively close to the guiding edge. When a line spaced a further distance from the guiding edge is to be drawn, the drafting tool is inverted, and the convexly curved engaging side 18 is placed against the guiding edge and moved along in the direction of its length in the same manner, the drafting instrument engaging the inner edge of the circle at a point 28 and the point of tangency being maintained with the guiding edge at a point 30.

In practice, it was found that the proportions of the Width of the tool to the length thereof should be about one to one and one-half. It will also be observed that a line 32 drawn from the point 24 of the inner edge of the circle or opening 12 to a point 34 where the upper end of the curved line 16 meets the radius of the leading edge 20 forms an angle with respect to a longitudinal line 36 passing through the center of the opening, and that a similar line 38 drawn from the point 28 to a corresponding point 40 on the engaging side 18 forms an angle with respect to said center line which is equal to said first angle so as to maintain similar proportions of the length of the curved engaging edge with relation to the spaced distance of the line drawn from the edge of the guiding surface.

FIG. 4 illustrates a modified form of the present drafting tool which comprises a. similar structure with the exception that the opening is made in a triangular shape, as indicated at 42, instead of the circular shape shown in FIG. 1. The triangular opening 42 is also offset from a longitudinal center line and is disposed with a straight side at right angles to the longitudinal center line. The corners of the triangle adjacent the transverse line may be rounded as shown, and in use the drawing instrument is placed in the opening adjacent a rounded edge and the tool is moved forwardly in the direction of the longer distance from the opening with the curved edge in engagement with a guiding edge. The tool shown in FIG. 4 may also be inverted to draw a parallel line s aced a different distance from the guiding edge, and the tool may be made in different sizes for drawing lines at different spaced distances from the guiding edge. It willbe understood that in practice the drafting tool is relatively small, as indicated in FIG. 5, the tools shown in FIGS. l-4 being greatly enlarged for clearance of illustration.

From the description thus far and with reference to FIG. 5, it will be seen that the present tool is capable of use in drawing parallel lines along straight guiding edges and also along concave and convex guiding edges. As illustrated in FIG. 5, the guiding member 44 comprises a French curve, only a portion of which is shown, and which is provided with a concave guiding edge 46 nd a convex guiding edge 48. In one position, as indicated at A, the tool 10 is arranged with its curved side 16 in engagement with the convex surface 48 of the French curve to draw a line 50 parallel to the guiding edge and spaced a relatively short distance therefrom. In another position, as indicated at B, the tool 10 is inverted and arranged with its curved side 18 in engagement with the concave surface 46 to draw a line 52 parallel to the guiding edge and spaced a greater distance therefrom. In practice, the drafting tool may be moved around either large or small curved guide surfaces while maintaining parallelism with the guiding surface as described. It will be understood that the radius of the curved engaging edges 16, 18 when guided along a concave edge cannot be greater than the radius of such guiding edge. In practice, the tool may be made of a size to accommodate such guiding surfaces while maintaining the same proportions.

In according with another feature of the present invention, the drafting tool 10 is constructed so as to prevent smearing of an inked line as the tool is moved along a straight or curved guiding edge. As herein shown, the tool is provided with longitudinal recesses 54, 56 on both faces thereof providing a central rib 58 and upper and lower bearing portions 60, 62 along one side, and upper and lower bearing portions 64, 66 on the other side, thus raising the central portion of the underside of the tool away from contact with an inked line when the tool is used with either face up. Furthermore, in order to avoid smearing of an inked line when the tool is moved about a guiding edge having a small radius, either concave or convex, the trailing end of the bearing portion 62 on the underside adjacent the edge 16 in FIG. 3 is cut away to a point 68 disposed forwardly of the opening 12. Likewise, when the tool is inverted, the trailing end of the bearing portion 64 is cut away to a corresponding point 70. Thus, in operation, when an ink drawing instrument, such as a Leroy pen, is used, the recessed portions and the cutaway portions will avoid contact with the inked line when drawing either straight or curved lines along a guiding surface.

From the above description it will be seen that the present tool is adapted for drawing lines parallel to a straight or curved guiding edge while maintaining uniform parallelism with the guiding edge, and that the present tool is also adapted to be used with a drafting pen without smearing the ink with the underside of the tool.

While the preferred embodiment of the invention has been herein illustrated and described, it will be understood that the invention may be embodied in other forms within the scope of the following claims.

Having thus described the invention, what is claimed is:

1. A drafting tool for drawing lines parallel to a guiding edge comprising a relatively small flat elongated and substantially rectangular sheet having a leading end and a trailing end and provided with a curved edge on one side of the sheet for engagement with the guiding edge, an opening adjacent the trailing edge of the sheet for receiving a line drawing instrument including an inking instrument of the type having a tubular ink dispensing nozzle, said curved engaging edge assuming a uniform position of tangency with respect to the guiding edge when the line drawing instrument is moved along within the inner edge of said opening nearest said engaging edge and in the direction of the leading end only of the tool to produce a line spaced equidistantly from and uniformly parallel to said guiding edge, said tool being of a size and shape such as to permit it to follow relatively small concave and convex curved surfaces of said guiding edge, said sheet being recessed longitudinally on the underside thereof providing bearing portions on opposite sides and a raised portion intermediate the bearing portions whereby to avoid contact of the tool with an inked line, the trailing end of the hearing portion adjacent the guide engaging edge of the tool being cut away for a short distance to avoid contact of the tool with an inked line when the tool is moved around curved guide edges. I

2. A drafting tool as defined in claim 1 wherein both faces of the tool are recessed and the trailing end of a corresponding bearing portion on the opposite side is also cut away to adapt the tool for use in an inverted position.

References Cited UNITED STATES PATENTS 991,693 5/1911 Brown 33-42 2,078,601 4/1937 Cutting 33107 X 2,212,703 8/1940 Suflich 33-41 X 2,509,164 5/1950 Nath 33-41 2,561,585 7/1951 McKillop 33-41 FOREIGN PATENTS 416,810 8/1925 Germany.

HARRY N. HAROIAN, Primary Examiner. 

